Landscape nails. You know, the ones that are a foot or more long. On top of these you can put a stainless steel washer so that you can pull the whole number up. MUCH better than re-bar, which rusts and pollutes the playa year after year. Galvanized you don't paint, the ones that are just steel you go ahead and paint. These can be hammered flush, and are easy to pull out. Great for tents.

You can get (though they aren't cheap) helical foundation anchors for bigger needs...like mobile home tie down points in size and just as strong.

Those are two of the possibilities.

Whatever you do, DO NOT have protruding re-bar. Somebody falls on it, they are in serious trouble unless it's properly capped. Please.